Most 300b amps have 7 watts output or so. Is your amp an SET (and therefore class A2) or is it push-pull?
If an SET, it is essential that the speaker have higher efficiency. I am running a 30-watt amp on speakers that are 98 db, in an average size room (17x23') and that seems to be about the minimum amount of power to get by. With SETs in particular (my amp is an OTL) you don't want to be driving the amp hard if you really want to hear what it can do (which will be good low level detail/transparency). That will require a speaker that is 98 db at the minimum, 103 would be nearly unlimited headroom.
That is why you see so many SET users using horns.
Plan B- if you really are considering a choice between these two speakers (both are excellent- FWIW I prefer the Ref3a in this case), then you will want to get a more powerful amp- one that has at least 100 watts. The 10 db difference in efficiency of speakers (91 to 101 db) translates into a 10X power difference.
If an SET, it is essential that the speaker have higher efficiency. I am running a 30-watt amp on speakers that are 98 db, in an average size room (17x23') and that seems to be about the minimum amount of power to get by. With SETs in particular (my amp is an OTL) you don't want to be driving the amp hard if you really want to hear what it can do (which will be good low level detail/transparency). That will require a speaker that is 98 db at the minimum, 103 would be nearly unlimited headroom.
That is why you see so many SET users using horns.
Plan B- if you really are considering a choice between these two speakers (both are excellent- FWIW I prefer the Ref3a in this case), then you will want to get a more powerful amp- one that has at least 100 watts. The 10 db difference in efficiency of speakers (91 to 101 db) translates into a 10X power difference.